The corrosion behaviour of three Al-Si alloys was studied after galvanostatic passivation in 0.1 M sodium tartrate, sulfate and borate solutions using EIS techniques. The degree of passivation depends on the anion type, the degree of polarization and the alloy composition. It was also found that increase in pH led to a decrease in polarization resistance R-p. The effect of formation voltage, V-f, on the growth and dissolution kinetics of the oxide grown on the alloys was studied. The polarization resistance value increases as V-f increases up to a certain value; above this the R-p value decreases. This critical V-f depends on the alloy composition and the test solution. The kinetics of oxide layer dissolution in the absence and presence of Cl- ions was also studied. Increase in immersion time leads to a more severe attack by Cl-ions as shown by the decrease in the value of R-p. At low Cl-ion concentration the value of R-p is higher than that in chloride ion free sulfate solutions, because the rate of passive film repair is much higher than that of barrier layer dissolution. However, at high Cl- ion concentration penetration of Cl- through defects in the barrier layer leads to formation of an oxyhalide layer.